Histocompatibility Leukocyte Antigen‐A2‐restricted and Tumor‐specific Cytotoxic T Lymphocytes from Tumor‐infiltrating Lymphocytes of a Patient with Testicular Embryonal Cancer

T lymphocytes play an important role in tumor rejection. To understand T cell‐mediated specific immunity at the tumor site of testicular embryonal cancer, we investigated whether interleukin‐2 (IL‐2)‐activated tumor‐infiltrating lymphocytes (TIL) of a patient with testicular embryonal cancer show histocompatibility leukocyte antigen (HLA)‐class I‐restricted and tumor‐specific cytotoxicity. We established a CD3(+)CD4(‐)CD8(+) cytotoxic T lymphocyte (CTL) line from the IL‐2‐activated TIL of a 37‐year‐old patient with testicular embryonal cancer. A 6 h (51)Cr‐release assay was performed to measure the cytotoxicity of the CTL. The CD3(+)CD4(‐)CD8(+) CTL line showed cytotoxicity against HLA‐A2(+) tumor cells, including freshly isolated autologous tumor cells, adenocarcinoma cell lines from various organs (lung, breast, pancreas, colon and kidney) and squamous cell carcinomas (esophagus and oral cavity). No other cell lines examined, including an autologous tumor cell line and HLA‐A2” tumor cell lines, were lysed by this CTL line. These results suggest the existence of HLA‐A2‐restricted and tumor‐specific CTL at the tumor site of testicular embryonal cancer.